KANSAS CITY, Mo. — When Dwayne Throneberry closed his haunted house, The Main Street Morgue, two years ago, he swore he had shaken his last skeleton at his last screaming teenager.

A plan to rebuild downtown Kansas City, including a new corporate headquarters for tax-prep giant H&R Block Inc. and an entertainment district, had claimed the building in which the Morgue had terrorized for decades.

Throneberry, who already had laid to rest two haunted houses nearby, said he’d had it with the headaches endemic in the industry and what he considered a lack of respect for his business by city officials.

But as the autumn chill began to creep back into Kansas City, which at one time counted more than a dozen haunted houses, Throneberry found himself in an old, 60,000-square-foot warehouse, assembling vampire forests and plugging in the sound machine.

“When I saw the inside, I knew I would build a haunted house here,” he said, taking a break from nine months of getting The Morgue ready. “I saw the dungeon in the basement. I saw Frankenstein’s laboratory on the fourth floor.”

Haunted houses have long been a tradition of Halloween, evolving from Jaycee charity tents and cold bowls of spaghetti “innards” to the sophisticated spook factories of today featuring movie-quality makeup and special effects. Long lines of thrill-seekers pay up to $20 or $30 apiece for a half-hour or more of controlled fright.

But those in the business say haunted houses, a growth industry only five years ago, have reached their peak. Urban renewal in many of the nation’s bigger cities has cut off operators from cheap locations, safety regulations have driven up the cost of doing business and outfitting the haunted house with the latest animatronic zombies or computer controlled ghouls has become an expensive arms race few can keep up with. Haunts built into existing amusement parks also have put pressure on their unaffiliated brethren.

“So many people who get in the business are artist-types who enjoy scaring people and don’t understand that if you don’t have the money, you don’t get to play anymore,” said haunted house designer Leonard Pickel, who edits the industry magazine Haunted Attractions. “Scaring people is easy. Making money scaring people is a lot harder.”

It’s difficult to determine how many haunted houses there are now. Excluding Halloween-themed attractions like hayrides, pumpkin patches and corn mazes, Pickel estimated there are between 3,000 and 5,000 haunted houses operating this year.

Larry Kirchner, president of the St. Louis-based International Association of Haunted Attractions, guessed lower, saying there are probably about 600 professional events, the remaining being run by charities.

Whatever the number, observers say there are fewer haunts today than there were 10 years ago. Today’s haunts, they say, are for the most part economically healthier and better-run.

“The people who are doing it now really want to be in the business,” Kirchner said.

Kansas City is an anomaly in the haunted house world because the city’s haunts are so big.

The four main houses — The Morgue, The Edge of Hell, The Beast and Catacombs — are all located in empty, multistory warehouses in the town’s old industrial neighborhood known as the West Bottoms. Combined, the houses attract around 100,000 people during the Halloween season.

Operators are reluctant to discuss exactly how much they spend on the houses and how much they make, but the math shows the revenue can be substantial.

Throneberry, for example, estimates he’ll get 1,000 thrill-seekers on a busy Saturday night, charging $20 a head. His season began Sept. 30, though some houses start as early as late August.

The Edge of Hell is the oldest house, moving to the area in 1989 but operating in other locations since 1975. The show, featuring 250 part-time actors, focuses less on gore and more on scenes that play on common fears like darkness, giant snakes and enclosed spaces. Customers end their journey on a four-story slide into Hades.

Its sister house, The Beast, sits a couple blocks over and is considered pioneering for its nonlinear format, including a quarter-acre “werewolf forest” that requires visitors to find the exit in near-darkness while avoiding patrolling monsters.

“It’s a hard job,” said Amber Arnett-Bequeaith, vice president of Full Moon Productions, which runs the two houses. “In a theater you do your job once. In our theater, you do your job 500 times a night.”

Catacombs, which leans more on the bloody side, is operating in limbo this year after its owner, Dennis Kingsolver, died this summer after he fell down an elevator shaft while working on his attraction.

“I love holidays, but (Halloween) is the only holiday that’s unscripted,” said Throneberry. “As a creator, or producer — and this is live interactive theater — there’s no limit to what I can do.”